Range Ambiguous Clutter Suppression for Airborne Radar Using Pulse Phase Coding

Airborne radars often operate at medium to high pulse repetition frequencies, inevitably leading to range ambiguity. When operating in non-side-looking modes, there is a variation in the Doppler frequencies of clutter at different ranges, indicating range dependency of the clutter. Such range ambiguity and range dependency significantly degrade the performance of traditional space-time adaptive processing (STAP). To address this issue, we introduce the application of pulse phase coding in airborne radar for suppressing range ambiguous clutter. At the receiver, using decoding that corresponds to the transmitted phase pulse coding prevents signals from other range regions from coherently accumulating and thus suppresses them, enabling the extraction of signals from a specific range region. This approach allows for the separate extraction of signals from each ambiguous range region, effectively resolving the range ambiguity of the signal. The clutter associated with range dependence in each range region is then addressed through Doppler compensation. Finally, STAP is employed to effectively suppress the clutter from each range region. Simulation results are provided to demonstrate the performance of the proposed method.